Engineers at Northrop Grumman's Rancho Bernardo plant will help design an unmanned airship that's capable of lingering in the skies above Afghanistan for up to three weeks at a time to provide surveillance and intelligence data for U.S. Army troops.

The Defense Department awarded Northtrop Grumman $517 million to build three so-called Long Endurance Multi-Intelligence Vehicle (LEMV) systems, each which will be longer than a football field and capable of flying more than three miles high. They're expected to be ready for testing in the Middle East within 18 months.

"We don't know how many people we'll use from the San Diego area but we will rely on our engineers there for help because of their expertise with unmanned aerial vehicles," said Dianne Baumert-Moyik, a spokeswoman for Northrop Grumman Aerospace Systems in Bethpage, N.Y.

Northrop Grumman's Rancho Bernardo plant designed the high-flying Global Hawk spy drone, which has been widely used throughout the Middle East.

The new LEMV is meant to perform "persistent eye" surveillance, which involves monitoring specific areas for long periods of times to identify potential threats. The airship will rise to altitudes of 20,000 feet and relay data to ground commanders. Northrop said in a statement "this disruptive innovation must meet the Army's objective of a persistent unblinking stare while providing increased operational utility to battlefield commanders. Part of our innovative offering includes open architecture design in the payload bay to allow sensor changes by service personnel in the field."

Insurgents have made wide use of rocket-propelled grenades in such places as Baghdad. However, defense analysts say that such shoulder-fired rockets generally cannot travel more than 3,000 feet, making them useless against a high flying drone. And insurgents do not have a fleet of drones like Predator, an unmanned aircraft designed at General Atomics Aeronautical Systems in Poway that can fire sophisticated air-to-ground missiles at distant targets.

Media outlets in Pakistan have claimed on several occasions that U.S. drones have been shot down over the past couple of years. But American officials have generally denied such reports or said that drones that did go down experienced technical problems that caused them to crash.

The persistent eye approach to surveillance "is like the stake-outs the FBI used to do against gangsters," said John Pike, a defense analyst at Globalsecurity.org. "The FBI would set up across the street from the gangsters and photograph them. This (airship) is a war-time version of staking out gangsters."

Helium-filled blimps were used by the U.S. Navy in World War II.— US Navy

Helium-filled blimps were used by the U.S. Navy in World War II.
/ US Navy

Other types of unmanned vehicles have been used to watch for the planting of roadside bombs in Iraq. And during World War II, the United States used blimps that could stay aloft up to 60 hours to search for submarines, aid in search and rescue and collect information for warships escorting convoys.